The present inventive concept relates to a hard disk drive (HDD). More particularly, the inventive concept relates to the actuator of a HDD which carries a magnetic head for reading/writing information from/onto a disk.
Referring to FIG. 1 a conventional HDD includes a disk 10 having a plurality of tracks containing information, a magnetic head 20 for reading and recording information from and onto the tracks of the disk 10, and an actuator for moving the magnetic head 20 over the disk 10. The actuator includes a swing arm 31 that is rotatable about an axis 35, and a voice coil motor 32 that rotates (drives) the swing arm 31. The magnetic head 20 is supported by an end of the swing arm 31.
Thus, during a read/write operation of the HDD, the voice coil motor 32 rotates the swing arm 31 in a first direction about axis 35 to position the magnetic head 20 over a selected track(s) of the disk 10 where the magnetic head reads/records information from/onto the disk 10 while the disk 10 is rotated. A suspension 33 at the end of the swing arm 31 elastically supports the magnetic head 20 so that the magnetic head 20 floats above the disk 10 during the read/write operation. In a stop mode, the voice coil motor 32 rotates the swing arm 31 in a second direction about axis 35, i.e., a direction that is opposite to the first direction, to move the magnetic head 20 off of the disk 10. At this time, an end tab 34 of the swing arm 31 is moved along and comes to rest on a ramp on 40 to “park” the magnetic head 20. A latch 50 locks the swing arm 31 while the magnetic head 20 is parked.
The angle at which the magnetic head 20 is oriented relative to a track of the disk 10 during a read/write operation in which the head 20 is positioned over the track is referred to as a skew angle. As described above, the swing arm 31 of the actuator is supported so as to rotate about a fixed axis 35. Accordingly, the skew angles between the magnetic head 20 and the tracks of the disk 10 vary. The greater the skew angle, the lower the recording density can be for a particular track wherein the recording density is the amount of information that can be stored per unit area on the disk.
In this respect, as illustrated in FIG. 2A, when the skew angle between a track 11 of a disk and the magnetic head 20 is 0 degrees, the track width may be optimally minimal and so the recording density for the track 11 may be maximal. However, the skew angle cannot be 0 degrees for all of the tracks because the disk 10 is fixed in place about an axis of rotation and the magnetic head 10 is rotated about an axis 35 that is spaced therefrom. FIG. 2B illustrates an example of a track 11 for which the skew angle is about 15 degrees. In this case, the width W of the track needs to be greater than that for cases, such as that illustrated in FIG. 2A, in which the skew angle is smaller to prevent interference between adjacent tracks 11. Thus, the recording density of the track 11 shown in FIG. 2B is less than that of the track 11 shown in FIG. 2A.
Taking the above into consideration, it is advantageous to minimize the amounts that the skew angles deviate from 0 degrees across the disk 10, i.e. for each of the tracks of the disk 10. To this end, lengthening the swing arm 31 has been considered. However, lengthening the swing arm 31 requires that the size of the HDD also be increased. Such a solution unavails itself to meet the current demand for smaller and lighter HDDs. Also, it is difficult to manufacture a practical and reliable HDD having a relatively long swing arm 31. In particular, technical problems arise with respect to the reading/writing of information when the swing arm 31 is relatively long such that the read/writing of information is not carried out in a limited space.